• Login
    View Item 
    •   Maryland Shared Open Access Repository Home
    • ScholarWorks@UMBC
    • UMBC Interdepartmental Collections
    • UMBC Theses and Dissertations
    • View Item
    •   Maryland Shared Open Access Repository Home
    • ScholarWorks@UMBC
    • UMBC Interdepartmental Collections
    • UMBC Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Mechanical Properties of Human Tooth Enamel: Patient Age and Spatial Distribution

    Files
    342.pdf (11.96Mb)
    Permanent Link
    http://hdl.handle.net/11603/566
    Collections
    • UMBC Graduate School
    • UMBC Mechanical Engineering Department
    • UMBC Student Collection
    • UMBC Theses and Dissertations
    Metadata
    Show full item record
    Author/Creator
    Unknown author
    Date
    2008-08-27
    Type of Work
    application/pdf
    Text
    theses
    Department
    Mechanical Engineering
    Program
    Engineering, Mechanical
    Rights
    This item may be protected under Title 17 of the U.S. Copyright Law. It is made available by UMBC for non-commercial research and education. For permission to publish or reproduce, please see http://aok.lib.umbc.edu/specoll/repro.php or contact Special Collections at speccoll(at)umbc.edu.
    Distribution Rights granted to UMBC by the author.
    Subjects
    Engineering, Materials Science (0794)
    Abstract
    In this study the influence of aging on the mechanical behavior of human enamel was evaluated using 3rd molars from young (18-30 years) and old (55) patients. The elastic modulus and hardness were quantified using nanoindentation as a function of distance from the Dentin Enamel Junction (DEJ) and within three different regions of the crown (i.e. cervical, cuspal and inter-cuspal enamel). The apparent fracture toughness of human enamel was estimated using the indentation fracture resistance test. The hardness, elastic modulus and apparent fracture toughness were then used in estimating the brittleness according to a model that accounts for the competing dissipative processes of deformation and fracture. The brittleness of human enamel was compared to that of selected dental restorative materials (i.e. porcelain, ceramic and micaceous glass ceramic (MGC)) that are used for crown replacement. Results of the evaluation showed that the elastic modulus and hardness increased with distance from the DEJ in the all three regions examined, regardless of patient age. The largest increases with distance from the DEJ occurred within the cervical region of the old enamel. Overall, the results showed that there were no age-dependent differences in the properties of enamel near the DEJ. However, near the tooth's surface both the hardness (0.025) and elastic modulus (0.0001) were significantly greater in the old enamel. At the surface of the tooth, the average elastic modulus of old enamel was nearly 20% greater than that of the enamel from young patients. The apparent fracture toughness of the young and old enamel ranged from 0.74 to 0.92 MPa*m0.5 and from 0.67 to 0.88 MPa*m0.5, respectively. The old enamel had significantly lower toughness than the young enamel at the outer surface. The average brittleness of the young and old enamel increased with distance from the DEJ. For the old enamel the average brittleness increased from approximately 300 µm-1 at the DEJ to nearly 900 µm-1 at the occlusal surface. While there was no significant difference between the two age groups at the DEJ, the brittleness of the old enamel was significantly greater (and up to four times higher) than that of the young enamel near the occlusal surface. The brittleness numbers for the restorative materials were up to 90% lower than that of the old enamel at the occlusal surface. Based on results of this study, it was concluded that the brittleness index could serve as a useful scale in the design of materials used for crown replacement, as well as a quantitative tool for characterizing degradation in the mechanical behavior of enamel.


    Albin O. Kuhn Library & Gallery
    University of Maryland, Baltimore County
    1000 Hilltop Circle
    Baltimore, MD 21250
    www.umbc.edu/scholarworks

    Contact information:
    Email: scholarworks-group@umbc.edu
    Phone: 410-455-3021


    If you wish to submit a copyright complaint or withdrawal request, please email mdsoar-help@umd.edu.

     

     

    My Account

    LoginRegister

    Browse

    This CollectionBy Issue DateTitlesAuthorsSubjectsType

    Statistics

    View Usage Statistics


    Albin O. Kuhn Library & Gallery
    University of Maryland, Baltimore County
    1000 Hilltop Circle
    Baltimore, MD 21250
    www.umbc.edu/scholarworks

    Contact information:
    Email: scholarworks-group@umbc.edu
    Phone: 410-455-3021


    If you wish to submit a copyright complaint or withdrawal request, please email mdsoar-help@umd.edu.